Barnacles are filter feeders that populate the coastlines of countries around the world. Fertilisation is external, and microscopic larvae develop. The larvae live for a time as plankton in the surface layer of the sea before settling and cementing onto rocks, where they metamorphose into the sessile adults. The adults of two species of barnacle, Chthamalus stellatus and Balanus balanoides, are found on rocks in the inter-tidal zone of exposed shores in Scotland. Chthamalus, the smaller of the two barnacle species, is found in the upper tidal zone, whilst the larger Balanus extends to the low-tide mark. If Balanus is absent, Chthamalus can grow throughout the inter-tidal zone. Predators of the adult barnacles are found throughout and below the inter-tidal zone. Predatory starfish are predominantly found below the low-tide mark, whilst predatory whelks and fish may feed in the inter-tidal zone.
Algae are dominant below the low-tide mark.
Question
Discuss how different biotic and abiotic factors act to determine the fundamental and realised niches of these two species, Chthamalus stellatus and Balanus balanoides.
The adults of two species of barnacle, Chthamalus stellatus and Balanus balanoides, are found on rocks in the inter-tidal zone of exposed shores in Scotland. Chthamalus, the smaller of the two barnacle species, is found in the upper tidal zone, whilst the larger Balanus extends to the low-tide mark. If Balanus is absent, Chthamalus can grow throughout the inter-tidal zone.
Predators of the adult barnacles are found throughout and below the inter-tidal zone. Predatory starfish are predominantly found below the low-tide mark, whilst predatory whelks and fish may feed in the inter-tidal zone.
Algae are dominant below the low-tide mark.
Question
Discuss how different biotic and abiotic factors act to determine the fundamental and realised niches of these two species, Chthamalus stellatus and Balanus balanoides.